The invention relates to a method for introducing and incinerating solid combustible waste, such as automobile tires, in a rotary kiln. Furthermore, the invention relates to an apparatus for carrying out the method.
It has proven to be advantageous both from an economic and environmental viewpoint to dispose of various types of combustible waste by incineration in a rotary kiln, for example for cement production, in combination firing with the normal fuel. If the waste is liquid, gaseous or pulverulent, the waste can normally be incinerated by using known burner equipment. However, if the waste is in solid form, with its lump size being such that the single lumps cannot be conveyed through the kiln by means of the gas stream, specialized methods are needed to inject the waste sufficiently far into the rotary part of the kiln so that complete incineration is achieved before the waste reaches the outlet of the kiln. This applies particularly to long rotary kilns where firing from the inlet end of the kiln cannot be applied due to the temperature here being inadequate for complete incineration to be achieved.
Several examples of methods and apparatus for burning solid waste in rotary kilns are known from the patent literature.
The U.S. Pat. No. 4,850,200 indicates a method for firing solid waste through the shell of the rotary kiln via a sluicing arrangement. The U.S. Pat. No. 4,984,983 further mentions the possibility of introducing waste through the kiln shell, mentioning also an ejector being capable of injecting the waste items into the kiln.
The aforementioned methods and apparatus involve a number of disadvantages. For one thing, the mechanical construction of the sluicing arrangement is very complicated, and that part of its feed pipe which is lying within the kiln shell is subjected to substantial mechanical and thermal impacts, and this may reduce the service life of the equipment.